The invention relates to embolism-preventing devices, and more particularly, to a device that prevents the free flow of embolism-creating particles that are created during predilation of a vessel or attachment of a stent therein.
A stent is a flexible, generally cylindrical object that is typically made of expandable wire mesh. Stents show great promise in opening blocked fluid vessels in the body and in maintaining those vessels in an open state to allow free fluid flow therethrough. Stents have been designed for blood vessels, the urinary tract, the trachea, and other fluid systems in the body.
A stent may be used to open a vein or artery that is blocked by fatty or calcified deposits or other obstructions. A typical method of using such a stent includes inserting a guide wire into the artery and sliding a catheter along the guide wire to the area affected by the deposits. The catheter carries a non-expanded stent thereon, and the stent is positioned adjacent the deposits. The catheter includes a system for expanding the stent, and this is typically done by providing a balloon that is disposed underneath the stent and connected to a passage or lumen within the catheter. When the stent is properly positioned, a burst of air or fluid through the catheter expands the balloon, which in turn permanently expands the stent until the stent contacts the interior wall of the vessel and has a diameter that is substantially the same as the artery. In this manner, the stent traps the fatty deposits against the interior wall of the vein. The catheter is removed from the artery, but the stent remains in the artery to maintain the artery in an open state so that blood may flow freely therethrough.
Although the stent is intended to trap deposits against the interior wall of a vessel, a portion of the deposits may become dislodged from the wall along the ends of the stent as the stent is being placed against the wall. Each dislodged deposit, or embolus, is carried along by the blood flow until it becomes lodged or trapped in a smaller vessel to create an embolism. Since embolisms reduce or cut off blood flow, damage to the body may result, such as tissue damage, heart attack, stroke, or even death.
Researchers have developed devices to eliminate embolus formation during stent attachment. However, these devices are typically bulky and separate from the stent-carrying catheter, and are therefore difficult to insert into the vessel while the catheter is also present in the artery. Furthermore, the balloon that expands the stent cuts off blood flow in the vessel when it is expanded. Because of the difficulty of simultaneously inserting a catheter and a separate embolism prevention device, the blood flow may be constricted or occluded for as long as ten minutes. This causes a deficiency of blood to parts of the body due to the obstruction of the artery. This condition is known as ischemia, and may result in tissue damage.
Emboli may also be created by balloons that are used in predilation systems. The balloon is attached to a catheter, which is positioned in an artery, and the balloon is expanded to dilate the vessel. Emboli created by predilation systems pose serious health risks, as described above, yet known predilation systems do not adequately prevent or remove emboli from the bloodstream.
The invention is a stent delivery system for use in a fluid conduit in a body. The system includes a catheter that is configured to be placed into a designated region of the conduit. A stent is configured to be moved into the designated region of the conduit by the catheter and placed upon an interior wall of the conduit. A conduit blockage mechanism is mounted on the catheter distal from the stent and is configured to block the conduit while the stent is being placed upon the interior wall.
Another aspect of the invention provides a predilation system for use in a fluid conduit in a body such conduit includes but are not limited to the carotid arteries, renal arteries, peripheral arteries, saphenous vein grafts and the coronary arteries. The system includes a catheter that is configured to be placed into a designated region of the conduit, a conduit dilation mechanism that is configured to be moved into the designated region of the conduit by the catheter to selectively contact an interior wall of the fluid conduit, and a conduit blockage mechanism that is mounted on the catheter distal from the conduit dilation mechanism. The conduit blockage mechanism is configured to block the conduit while the conduit dilation system is contacting the interior wall.
The invention also provides a method of preventing emboli from being created during a stent installation process. According to the method, a catheter is inserted into a bodily fluid conduit. The catheter has a stent and a conduit blocking mechanism mounted thereon at separate positions along the catheter. The conduit blocking mechanism is actuated, and the stent is installed onto an interior wall of the conduit. Embolism-forming particles created during the installing process are removed from the conduit. The conduit blocking mechanism is de-actuated, and the catheter is then removed from the conduit.